/* linux-2.6.6-rc2/fs/xfs/support/qsort.c */
/*
 * Copyright (c) 1992, 1993
 * The Regents of the University of California. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#ifdef __MACH__
#include <machine/types.h>
#include <sys/kernel.h>
#else
#include <linux/types.h>
#include <linux/kernel.h>
#endif /* __MACH__ */


#ifndef min
#define min(x,y) (x) < (y) ? (x):(y)
#endif /* min */

#ifndef COUNT 
/*
 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
 */
#define swapcode(TYPE, parmi, parmj, n) { \
 long i = (n) / sizeof (TYPE); \
 register TYPE *pi = (TYPE *) (parmi); \
 register TYPE *pj = (TYPE *) (parmj); \
 do { \
 register TYPE t = *pi; \
 *pi++ = *pj; \
 *pj++ = t; \
 } while (--i > 0); \
}
#endif /* COUNT */

#ifdef COUNT   /* TIMING */
/*
 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
 */
#define swapcode(TYPE, parmi, parmj, n) { \
 long i = (n) / sizeof (TYPE); \
ADD_SWAP; \
 register TYPE *pi = (TYPE *) (parmi); \
 register TYPE *pj = (TYPE *) (parmj); \
 do { \
 register TYPE t = *pi; \
 *pi++ = *pj; \
 *pj++ = t; \
 } while (--i > 0); \
}
#endif /* COUNT  */

#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;

static __inline void
swapfunc(char *a, char *b, int n, int swaptype)
{
 if (swaptype <= 1)
 swapcode(long, a, b, n)
 else
 swapcode(char, a, b, n)
}

#define swap(a, b) \
 if (swaptype == 0) { \
 long t = *(long *)(a); \
 *(long *)(a) = *(long *)(b); \
 *(long *)(b) = t; \
 } else \
 swapfunc(a, b, es, swaptype)

#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)

static __inline char *
med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
{
 return cmp(a, b) < 0 ?
 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
}

void
sortValues (void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *))
{
 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 int d, r, swaptype, swap_cnt;
 register char *a = aa;

loop: SWAPINIT(a, es);
 swap_cnt = 0;
 if (n < 7) {
 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 pl -= es)
 swap(pl, pl - es);
 return;
 }
 pm = (char *)a + (n / 2) * es;
 if (n > 7) {
 pl = (char *)a;
 pn = (char *)a + (n - 1) * es;
 if (n > 40) {
 d = (n / 8) * es;
 pl = med3(pl, pl + d, pl + 2 * d, cmp);
 pm = med3(pm - d, pm, pm + d, cmp);
 pn = med3(pn - 2 * d, pn - d, pn, cmp);
 }
 pm = med3(pl, pm, pn, cmp);
 }
 swap(a, pm);
 pa = pb = (char *)a + es;

 pc = pd = (char *)a + (n - 1) * es;
 for (;;) {
 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 if (r == 0) {
 swap_cnt = 1;
 swap(pa, pb);
 pa += es;
 }
 pb += es;
 }
 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 if (r == 0) {
 swap_cnt = 1;
 swap(pc, pd);
 pd -= es;
 }
 pc -= es;
 }
 if (pb > pc)
 break;
 swap(pb, pc);
 swap_cnt = 1;
 pb += es;
 pc -= es;
 }
 if (swap_cnt == 0) { /* Switch to insertion sort */
 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 pl -= es)
 swap(pl, pl - es);
 return;
 }

 pn = (char *)a + n * es;
 r = min(pa - (char *)a, pb - pa);
 vecswap(a, pb - r, r);
 r = min((long)(pd - pc), (long)(pn - pd - es));
 vecswap(pb, pn - r, r);
 if ((r = pb - pa) > es)
   sortValues(a, r/es, es, cmp);     /* recursive invocation. */
 /* qsort(a, r / es, es, cmp); */
 if ((r = pd - pc) > es) {
 /* Iterate rather than recurse to save stack space */
 a = pn - r;
 n = r / es;
 goto loop;
 }
/* qsort(pn - r, r / es, es, cmp);*/
}
